Allelopathic Impacts of Cover Crop Species and Termination Timing on Cotton Germination and Seedling Growth

Abstract

The integration of cover crops into cotton (Gossypium hirsutum, L.) production remains challenging. One potential negative impact of cover crops on cotton is allelopathy. Proper selection of cover crop species and termination timing could potentially reduce the impacts of allelopathy on cotton seedlings. Two studies were conducted to determine cotton germination and growth sensitivity to cover crop leachate, which were measured using (I) five cover crops species, including: oats (Avena sativa L.), hairy vetch (Vicia Villosa), winter pea (Lathyrus hirsutus), winter wheat (Triticum aestivum), and annual rye (Lolium multiflorum), and (II) a blend of cover crops at four termination timings, including: at planting, three weeks prior to planting, six weeks prior to planting, and a split termination, where a 25 cm band in the top of the bed was terminated six weeks prior to planting, and the remaining cover crop was terminated at planting (referred to as strip 6-wk). Samples for Experiment I were collected on May 24th and for Experiment II on March 22nd (Strip/6-wk and 6-wk), April 30th (3-wk), and May 11th (at planting) in 2018. The effect of 0 (deionized water), 25, and 50 (v/v) cover crop leachate extract on cotton seed germination was evaluated in a series of controlled environmental studies. All cover crop species’ leachates negatively impacted cotton germination and seedling growth (p < 0.05). Germination inhibition rates declined numerically by species, with winter pea ≥ hairy vetch ≥ oats ≥ annual rye ≥ winter wheat at the 50 v/v concentrations. Winter pea germination inhibition on cotton equaled 47.0% and cotton radicle length was decreased by 62.8%. Termination at planting suppressed cotton germination more than the other termination timings, with the 50 v/v treatment resulting in a germination inhibition of 60.0%. Proper selection of cover crop species and termination timing prior to planting cotton will be critical in maximizing the benefits and minimizing the risks of a cover crop.

Allelopathic Potentiality of Euphorbia hypericifolia L. on Germination and Seedling Development of Sympatric Crops and Weeds

“…One of the Key members among plant categories are the invasive alien species which when anthropogenically or naturally introduced outside their natural abort, transit from feeble into compelling competitive species that impair the native flora. Plant invasion is a global environmental problem attributed to non-native invasive plants that recruit reproductive offspring, and usually in extremely large numbers that eventually spread rapidly in the novel habitat [1]. Such invasive-alien-species-driven activities that also result in environmental degradation and biodiversity loss have the potential to completely alter core structures and functions of recipient ecosystems [2] and [3].…”

Allelopathic Impact of Cover Crop Species on Soybean and Goosegrass Seedling Germination and Early Growth

“…The five aforementioned cover crop samples were prepared in a multistep process as described by Shekoofa et al [1]. The samples were oven-dried at 60 • C for 5 days, ground to pass a 1 mm screen, and then kept in a refrigerator at 2-4 • C until used.…”

“…The adoption of conservative farming practices, such as no-tilling systems, has increased the utilization of cover crops in agronomic systems [1]. Cover crops offer many potential benefits to a production field, including weed suppression, soil quality improvement, and soil water infiltration [2,3].…”

“…These known benefits are only part of the equation; naturally produced allelochemicals from cover crops could suppress herbicide-resistant weeds and support a sustainable agricultural production system [4]. However, research has also documented negative allelopathic effects on row crops planted into cover crop systems [5,6], specifically, the suppression of seedling growth on succeeding cash crops [1,7,8]. Allelopathy involves the positive or negative effects of a plant (donor), including microorganisms, on neighboring plants (targets) through the release of chemical compounds into the environment, mostly in the soil [4].…”

“…Understanding the link between cover crop management and allelopathic dynamics can help avoid negative impacts on the growth and productivity of the subsequent row crop [1,6]. It is important to determine the allelopathic compatibility of cover crop species with row crops before incorporating them into agronomic systems, as phytotoxins released by cover crops could affect the establishment of row crops [10].…”